Three-element carrier code arrangement



THREE-ELEMENT CARRIER CODEARRANGEMENT Filed June 10, 1938 I TIC/(ER TRANSMITTER I t MOTOR LOCAL TIC/(ER CLUTCH RECEIVER PATRONS SENDING DRUM COMMUTA 70/? 8 SE GMEN 7'5 REPEAT D/STANT r/cxm SPACE KEV G 6 RECEIVER PA mo/vs M SEND/N6 LOOP P] A I 76 A4 F/(KEQ T0 1 L WM/fl? INPUT CARR/ER LINE INPUT M CARP/ER LINE OUTPUT m RECEIVING RELAY M UNE WIND/N6 s m RECEIVING RELAY M KICK WIND/N6 s M lNVENTO/Q RECEIVING LOOP/1T F H. HANL EV BV s msmur TERMINAL PATH-12w or slam/.5 w PARTS W OF r/m-u/r m/o/ca TED v ATTORNEY Patented Feb. 25, 1941 UNHTED STATES PATENT OFFiQE THREE-ELEMENT CARRIER CODE ARRANGEMENT Application June 10, 1938, Serial No. 213,059

10 Claims.

This invention relates to telegraph systems and more particularly to a telegraph circuit by means of which three-element direct current signals are converted into three-element alternating current signals, transmitted over a single carrier channel, and thereafter reconverted to threeelement direct current signals.

Three-element direct current signals are used in certain telegraph systems, notably in wellknown stock quotation systems.

There are advantages well known in the telegraph art in the use of direct current signals in the local receiving circuit for the operation of telegraph printers. It is desirable for economic reasons to use a carrier channel in connecting Widely separated transmitting and receiving centers.

In cases, as say in said Well-known stock quotation service, a single transmitter, say in New York city, is connected to a number of local receivers, as well as to receivers in distant cities. It is desirable to generate direct current signals for transmission to the local stations. For the distant cities it is desirable for the economic use of the long connecting line to convert the direct current signals into alternating current signals for transmission over a carrier channel and then to reproduce the original signals at the distant cities to operate the local printers in these areas.

While it has been possible heretofore to transmit three-element signals over a carrier channel, as far as applicant is aware there are no known facilities for converting three-element direct current signals into three-element alternating current signals and thereafter reproducing signals of the original character.

It is an object of this invention to provide means for translating three-element direct current signals directly into three-element alterhating current signals and then reproducing, from these latter, direct current pulses of the original character.

A feature of this invention is the relay arrangement used to translate the three-element direct current signals into three-element alternating current signals at the input of the carrier channel.

A further feature of this invention is the relay arrangement used to reproduce the original signals at the carrier output terminal.

While this invention will be pointed. out with particularity in the appended claims, the invention itself both a to its further objects and features will be better understood from the detailed description hereinafter following when read in connection with the accompanying drawing representing an embodiment of the invention.

Fig. 1 of the accompanying drawing discloses a circuit by means of which three-element direct current signals are converted into threeelement alternating current signals. The alternating current signals are transmitted over a carrier channel to a distant receiving station where they are rectified and retranslated into three-element direct current signals of the original character.

Fig. 1A of the accompanying drawing shows in a series of diagrams the character of the signals transmitted over various parts of the circuit per Fig. 1.

The detailed description of the operation of the circuit is as follows:

Conductors Nos. 1 and 2 are connected to a well-known stock quotation ticker transmitter. A train of positive and negative battery pulses are transmitted over conductor 1- from a local transmitter through the winding of polar relay 4 to ground. The armature of rela 4 follows these pulses, being operated alternately to engage its marking contact M, and its spacing contact S. During the operation of relay 4 polar relay 3 is held on its marking contact M. How this is performed will be described hereinafter.

One side of the output from a source of alterhating current. I is connected to 2B which will simulate one side of a carrier channel extending to a distant station. The other side of said out put is connected through protective resistance 6 to 21 which will simulate the second side of a carrier channel which also extends to said distant station. With the armatures of both relays 3 and 4 on their marking contacts M, the full output from source I is impressed through protective resistance 6 on 20 and 2!. When the armature of relay 4 is operated to engage its spacing contact S, a direct shunt is closed around the alternating current source 1 and its protective resistance 6.

This shunt may be traced from the top terminal of resistance 6, through lead 24, the M contact and armature of relay 3, conductor 23, the armature and S contact of relay 4, conductor 22 and through conductor 25 to the bottom terminal of the alternating current source I. The resistance of the few feet of wire and the contacts in the shunt path is practically negligible as compared with the resistance of the carrier channel 2|] and 2| to the distant station. The current in the channel istherefore reduced practically to zero. Thus we find that we have full output current in the channel when relay 4 is on its M contact and no current when relay 4 is on its S contact.

The operation of relay 3 will now be described. Ground is normally connected to lead 2 in the connecting transmitter circuit. Current therefore normally flows through the upper winding of relay 3 from battery connected thereto. This current is in such a direction as to tend to operate the armature to engage its marking contact M. The current in the lower or biasing winding is in such a direction as to tend to operate the armature of relay 3 to engage its cOntact R. S. Under these conditions the effect of the current through the upper winding is stronger than the elTect of the current through the lower winding and the armature of relay 3 is operated to it M contact where it remains while relay 4 is reproducing the full positive and negative pulses from the transmitter to impress full current and zero current on the line.

Under certain circumstances it may be desirable to transmit a third current condition. In the case of the well-known stock quotation transmitter, a third condition, which is half of the full line current, either positive or negative, is transmitted to the local receiving tickers as a repeat space condition. This operation is used in ticker printer service principally for tabulation and indentation. In transmitting the signal a resistance is inserted in the transmitter circuit, in series with the transmitter output lead, which serves customers printers in the area local to the transmitter, to reduce the output current to either half of full positive or negative current. Heretofore, as far as applicant is aware, no circuit has been available to translate such a con dition at the input of a carrier in order to transmit such signals to distant centers. Applicants circuit performs this function in the following manner:

When the third current condition is to be transmitted, a relay in the local transmitter circuit, to which lead 2 is connected, is operated to open the connection thus removing ground from conductor 2 at the transmitter. The current in the upper winding of relay 3 thereupon falls to zero. The current in the lower or biasing winding of relay 3 is then effective to operate the armature of relay 3 to engage its contact R. S. R. S. is chosen to designate repeat space. The invention is not limited, however, to the transmission of a third current condition for this purpose only. The third current condition may be used to perform any of a wide variety of functions. Furthermore, while the invention is shown in connection with a well-known stock quotation transmitter and receiver it is understood that it discloses broadly a method of converting threeelement direct current signals into three-element alternating current signals and thereafter reproducing the three-element direct current signals.

When the armature of relay 3 is operated to engage its contact R. S. the alternating current source 1 and its protective resistance Ii are shunted by a circuit which includes resistance 5, to reduce the input into the carrier channel by half. This resistance can be chosen to give any desired input into the carrier channel, however. The armature of relay 4 may be operated to either its M or S contact, in response either to the half-positive or half negative current through the aforementioned resistance in the transmitter output lead in series with conductor l as the armature of relay 3 is operated to engage its R. S. contact. If the armature of relay 4 is on its M contact, the shunt may be traced from the upper terminal of resistance 6, through conductor 27, resistance 5, conductor 23, the armature of relay 3, contact R. S. and conductors 25 and 25 to the lower terminal of T. If the armature of relay 4 is on its S contact there is a path through the armature and S contact of relay 4 and conductor 22 in parallel with conductor 23, the armature and R. S. contact of relay 3 and conductor 25. Therefore. a repeat space signal of half full current may be transmitted regardless of the position of relay 4. Or relay 4 may be arranged so that it does not respond to half current without affecting the operation of the circuit.

At the output end of the carrier channel, the alternating current impulses are rectified by rectifier 8. Thereafter the three original current conditions, namely, full positive current, full negative current, and half current, either positive or negative are reproduced in the sys tem of relays 9, l0 and H together with their associated apparatus and connections in the following manner:

Relays 9, I0 and H are polar relays. Each has three windings. The top winding of relay 9 is a holding winding. The middle is a line winding. The bottom is a biasing winding. The top windings of relays Ill and II are known in the art as kick windings, The middle and bottom windings of each are holding windings. The relays are arranged so that all armatures are operated to their marking contacts M on full line current and to their spacing contact S on no line current. Relays l0 and H only respond to the half line current condition. The holding windings of all relays are poled so that the armature of each relay tends to be held on the contact to which it was last operated. The holding winding on relay 9 neutralizes some of the effect of relay 9 biasing winding when the relay armature is in its marking contact and adds to the effect of the biasing winding when the armature is on spacing. This makes the armature of relay 9 responsive only to full increase or decrease in line current. Relays IO and H are connected to the rectifier output through a kick circuit comprising the secondary of transformer 12. The relays are arranged so that their armatures will operate to their marking contacts M on either a hall or full increase in current and will operate to their spacing contacts s on either a half or full decrease in current.

The operation of these relays and their associated connections will now be described in detail.

Let it be assumed first that the armatures of all relays are on their marking contacts M. Let us assume also that the line current then falls to zero from full current. There is therefore no current flowing through the middle winding of relay 9. The current through the biasing or bottom winding of relay 9 tends to operate the armature to engage its S contact, While the armature of all the relays are still on M, a circuit may be traced from ground through resistance l6, through the top or holding winding of relay 9, the armature and M contact of relay 9, conductor 32, M contact and armature of relay l0, conductor 30 to negative battery 14. The efifect of this holding winding is to oppose the effect of the biasing current, which latter effect is stronger, however, and the armature of relay 9 operates to its S contact.

When the armatures of relays l0 and H are on their marking contacts M, there is a circuit from ground through resistance 11, the middle windings of relays ill and H, the M contact and armature of relay ll, through conductor 3| to positive battery id. The effect of current through the middle windings of each of these relays is to tend to hold their armatures on their M contacts. The circuit through the bottom windings of relays Ill and H is open at the S contact of relay it), when relay I9 is on its M con tact, so that the bottom windings on relays ill and i i are without effect for this condition.

As the rectifier output drops from full current to zero current there is a sudden decrease in current in the primary of transformer 12. This sudden change induces an electrornotive force in the secondary of transformer 12 and a flow of current through the top windings of relays l8 and l l. The effect of this current is to tend to operate the armatures of relays ac and H to their spacing contacts S. The effect is great enough to overcome that of the middle or holding windings tending to hold the armatures on their marking contacts M and the armatures of both relays are operated to engage their S contacts. All three relays therefore, 9, It and H, are operated to S by a decrease in current from full current to zero current.

When all three relays 9, l0 and II are on their S contacts, a path may be traced from positive battery i5 through conductor 3|, the armature and S contact of relay I, conductor 33, the S contact and armature of relay 9 to conductor I9. Thus We have full positive current supplied to any connecting circuit by conductor l9 for this condition.

When the armatures of the three relays 9, It] and il are operated to engage their S contacts the conditions of some of their various windings are changed. In the case of relay 9, there is no current in the line or middle winding. The bottom or biasing winding is not, of course, affected by the transfer and still operates with the same magnitude to hold the relay armature on its S contact. The direction of current flow through the top winding of relay 9 has been changed as it is now terminated in positive battery l5 instead of in negative battery l4. Since, when the armature was on M the direction of current flow through the top winding was such that the efiiect of the winding was to hold the armature against the M contact, when the polarity of the battery is reversed by the armature transfer the effect of the winding Will be to hold the relay on S. Thus when the armature of relay 9 is on S the eifect of the holding winding is to augment the effect of the biasing winding.

The magnitude of the effect of these two windings on relay 9 is such that itrequires the effect or :full line current in the middle or line winding to overcome it. The relay armature is therefore not responsive to a change from zero line current to half line current but does respond by operating to M, whenever full line current fiows in the line.

When the armature of relay 9 is on M and the line current is reduced from full current to half current, the effect of the half line current will be to tend to hold the armature on M. The cumulative efiect of this Winding together with that of the top or holding winding is adequate to prevent the effect of the ibiasing winding from operating the armature of relay 9 to S.

When relay 9 line current changes from half current to zero current the resulting relay winding conditions are the same as .for the change from full line current to zero line current described above and the relay armature is operated to S. From this description it should be apparent that the armature of relay 9 engages its marking contact M on full line circuit, its spacing current S on zero line current, that it does not respond to a change from full or zero current to half current and that it is operated to the marking contact M and to the spacing contact S on a change from half to full line current and from half to zero line current respectively.

When the armatures of relays IE) and H are on their S contacts, the circuit through their middle windings heretofore traced is broken at the M contact of relay H. A new circuit is established through the bottom windings of these relays, however, from ground through resistance IS, the bottom windings of relays I l and H], the S contact and armature of relay it], through conductor 30 to negative battery 14. The effect of the current through these bottom windings of relays l0 and H is to tend to hold the armature of each relay against its S contact. The magnitude of the effect of each of the holding windings, whether for the marking or spacing condition, is not large however. It is just great enough to insure contact while the armatures engage either contact. Relays Ill and l! armatures are therefore responsive to the eiTect produced in their kick windings by small changes in line current. Therefore if the armatures of relays IE! and H are engaging their S contacts for the zero line current condition, a chan e to half current will produce an effect in the kick winding sufficient to operate the armatures of each relay to its M contact. A further increase in line current from the half to the full current condition, of course, can produce no further effect, because the effect in the kick windings will be in a direction to operate the armatures toward the M contacts which they are already engaging.

A decrease in the line current from full current to half current will operate the armatures of relays I 0 and II to their S contacts. A further decrease from half line current to zero line current can have no effect.

Thus it should be apparent that the armatures of relays H] and II will engage their M contacts on any increase in current or on full line current and that they will engage their S contacts on any decrease in current or on zero line current. When the armatures of all relays 9, HI and I l engage their M contacts, a path may be traced from negative battery I l, through conductor 3%), the armature and M contact of relay in, conductor 32, the M contact and armature of relay 9 to conductor l9 supplying full negative current to any connecting circuit. When the armature of relay 9 engages its M contact and the armatures of relays H3 and H have been operated to engage their S contacts as a result of a decrease in current, a path may be traced from negative battery I4, through resistance 28, the I M contact and armature of relay 9 to conductor 19 furnishing reduced negative current to any connecting circuit. When the armature of relay 9 is on its S contact and the armatures of relays Ill and II have been operated to engage their M path may be traced from positive battery I5 through resistance 29 and the S contact and armature of relay 9 to conductor l9 supplying reduced positive current to any connecting circuit. The resistances 28 and 29 may be of any value to give any reduction in current. When the invention is used in connection with a Dow- Jones ticker receiver, the resistances are chosen so as to give the reduction in current required for the repeat space condition which is a reduction to half current.

Mention has been made that the half current signals may be either positive or negative. The well-known stock quotation transmitter is arranged so that alternate positive and negative battery pulses are transmitted from positive and negative battery sources through a commutator. In order to save operating time which would otherwise be lost if the half current pulse used for repeat space had to be of a particular polarity, this condition is produced by inserting a resistance in series with the lead from the commutator and thereupon stopping the commutator so that a single repeat space pulse or a series of repeat space signals may be either positive or negative. We have seen that, at the input to the carrier channel, the half current pulses will be translated into alternating half current pulses. At the output of the carrier channel if all relays are on M for the full current condition and a change to half current is made the armature of relay 9 remains on its M contact while the armature of relays In and II are operated to their S contacts. The result is reduced negative current from source l4 through resistance 28. If the armatures of all relays are on their S contacts for the zero current condition and a change to half current is made the armature of relay 9 remains on its S contact while the armatures of relays l0 and H are operated to their M contacts and the result is reduced positive current through resistance 29.

Signals identical in character with those transmitted by the well-known stock quotation transmitter to the receiving tickers in the same local areawith the transmitter are thus reproduced at the distant end of a carrier channel for operating receiving tickers at said distant point.

The character of the signals in the various parts of the circuit per Fig. 1 is illustrated in Fig. 1A to elaborate the description of the operation of Fig. 1, as a further aid to a ready understanding of the invention.

What is claimed is:

1. In a telegraph system, a direct current telegraph circuit connected to the input terminal of an alternating current telegraph circuit, means in said direct current circuit for transmitting a three-element direct current telegraph signaling code to said input terminal, means at said input terminal for impressing an alternating voltage of a single frequency only on said input, switching means and lumped impedance means both connected to said alter nating circuit at said input terminal, and means for operating said switching means. in accord ance with said direct current code to vary the amount of said impedance effectively in said alternating current circuit so as to translate said three-element direct current code into a three-element alternating code.

2. In a telegraph system comprising a carrier channel, an input terminal and an output tercontacts as a result of an increase in current, a

minal, a first relay and a second relay connected to said input terminal, means connected to said channel for impressing a single alternating voltage only thereon, variable impedance means connected to said channel, means connected to said first and second relays for operating said relays in accordance with a threeelement direct current telegraph code, means connected to said first relay for varying said impedance in accordance with two elements in said code, and means connected to said second relay for varying said impedance in accordance with the third element of said code so as to translate three-element direct current signals into three-element alternating current signals.

3. In a telegraph system, a single carrier channel, means for establishing a single frequency alternating current in said channel for a first telegraph signal element, means for modulating the amplitude of said current only in two steps for a second and third telegraph signal element, an output terminal connected to said channel, translating means comprising a rectifier and three polar relays for translating said three-element alternating current signals re ceived from said channel into three-element direct current signals.

4. A single carrier channel telegraph output terminal comprising a first, second and third polar relay, means for receiving three current conditions from said carrier channel means connected to said first relay for operating said relay in response to two of said conditions only, and means connected to said second and said third relays for operating said second and third relays in response to all of said conditions.

5. The method of transmitting three-element direct current signals long distances, said three elements including two elements of a first polarity of current, said two elements differing in magnitude and the third element being of a second polarity, which comprises in the order named translatingsaidthree-element signals into signal elements of a single frequency alternating current, transmitting said alternating current from a transmitting to a receiving station, thereafter rectifying said alternating current, retranslating said rectified current into three-element signals of the original character and retransmitting said retranslated signals.

6. A method of telegraph communication comprising generating a plurality of direct current signal elements of opposite polarities and including currents of different magnitudes and of the same polarity, translating said direct current elements into signal elements of a single frequency alternating current in an operation comprising a first relay switching operation, transmitting said alternating current from a transmitting to a receiving station, thereafter rectifying said alternating current, retranslating said rectified current in a second relay switching operation into direct current signals of the original character and retransmitting said retranslated signals.

7. In a telegraph system, means for generating three-element direct current signals including signals of opposite polarity and different magnitudes, means for translating said signals into signals of a single frequency alternating current of diiferent magnitudes, means for retranslating said alternating current into threeelement direct current signals of the original character and means for retransmitting said retranslated signals.

8. In a telegraph system, a telegraph input terminal, a telegraph output terminal, means for establishing a single frequency alternating current in the path between said terminals, means at said input terminal for varying the amplitude of and short-circuiting said current in accordance with a three-element telegraph signaling code and relay means at said output terminal for translating said varied and short-circuited current into direct current pulses of a first and second polarity and a first and second amplitude.

9. In a. telegraph system, an output circuit for a telegraph carrier channel comprising a rectifier, an output circuit for said rectifier comprising a series circuit including a winding on a polar relay and a primary winding on a transformer.

10. In a telegraph system in combination a rectifier, a transformer having a primary and secondary winding and a first, second and third polar relay, a winding on each of said relays, an output circuit for said rectifier including a series connection through said winding on said first polar relay and said primary winding and a series connection including said secondary and said windings on said second and third polar relays.

FRAENK HAROLD HANLEY. 

